Lord Thane I think the question is IF completely getting rid of pre re is the answer, or making it so that the purpose of pre re is to be able to fight larger kingdoms and not be used in a toxic manner.
A pre could be valid only if the initial kingdom bottom feeds. The defending kingdom then gets a pretal token to send to an ally. That pretal token can only be used by a kingdom whose KS is capped when added to the kingdom who sent it VS the original attacking kingdom KS.
Cli could prohibit bottom feeding as stated in your last post and then make it so a large kingdom cant castle pass to an ally to remain completely untouchable. They still get their castle protection from cli but the pretal token can be used in accordance with the retal they gave, albeit by two much smaller kingdoms. Balance could be set so defending is still possible, but so is battling bottom feeders.
The pretal might rarely break but it would atleast give smaller kingdoms and casual players a means of having some sort of possible retribution.
If you attack kingdoms within your size limit, pretal does not exist and kingdoms can enjoy the attrition strategy of CLI with rebuild protection. Its a means of satisfying both sides of the argument.